U.S. District Judge James Boasberg in Washington, D.C., has rejected their arguments, ruling that the "agency's actions were not arbitrary, capricious, an abuse of discretion or otherwise not in accordance with law."

Farming has long been used on national wildlife refuges for multiple purposes like habitat restoration, which involves destroying invasive species to make room for native plants, the ruling said.

U.S. Fish and Wildlife officials in the Midwest were aware that refuges in eastern states had been sued over allowing transgenic crops on such land, and decided to develop an environmental assessment of the practice.

The agency originally preferred taking no action, which would have allowed genetically engineered crops to continue being grown in refuges for multiple purposes.

In the final version of its environmental analysis, the agency instead chose to only allow transgenic crops to be grown for five years per tract, and only for habitat restoration objectives.

Plaintiffs claimed the agency's analysis didn't adequately consider the impact of increased herbicide usage on water and endangered species.

They also argued the analysis should have more closely looked at possible development of weeds resistant to glyphosate herbicides and cross pollination between transgenic and conventional crops.

Boasberg found that the Fish and Wildlife Service sufficiently studied these concerns and countered the arguments with scientific studies and mitigation measures.

"FWS's conclusions may not be what plaintiffs wish, but it cannot be gainsaid that they took a hard look at the issues," the judge said.